1. Field of the Invention
The present invention relates generally to thrust vector control systems and, more particularly, to synchronized forward and aft thrust vector control.
2. Prior Art
Referring to FIG. 1, thruster positioning mechanisms and systems are used on spacecraft 1 or similar bodies for the purpose of directing the propulsive force from a thruster. Such systems are often used to align the thrust vector 5 reaction through the center of mass 3 of the spacecraft 1 to enable straight line acceleration. Vectoring of the thrust away from the center of mass 3 is often done to initiate vehicle rotation or for course changing maneuvers. Such thrust vectoring is used to control the pitch and yaw rate of the spacecraft 1.
In zero-length launch of aircraft, the jet engine is used with a rocket motor to accelerate the aircraft to flying speed in a brief interval of time. In early designs of such aircraft, such as described in the patent to Mathiesel et al, U.S. Pat. No. 2,922,602, the rocket motor was positioned to direct its thrust through the center of gravity of the aircraft.
In later designs, wherein the jet engine is displaced from the longitudinal axis of the aircraft, the rocket motor is positioned to balance the respective aerodynamic, engine thrust and motor thrust moments around the aircraft center of gravity. A major problem of this later design encountered during zero launch is the control of the aircraft pitching moments which are dependent upon: the magnitudes and variations of engine and rocket motor thrust; the variations in the center of gravity during the boost phase; the variations in the aircraft aerodynamics; and the engine exhaust impingement on the rocket motor assembly.
It has been suggested in the prior art that a thrust vector control system (TVCS) be used with a control device in the rocket exhaust nozzle or aft of the rocket exhaust nozzle. Since the rocket motor is normally jettisoned after launch, such a control system would be jettisoned with the boost motor, thus increasing launch costs.
In addition, such conventional TVCSs located in the rocket exhaust nozzle require rapid response performance capability. Which, when coupled with a very high reliability requirement necessitates the need for a very complex and expensive TVCS.
In accordance with one embodiment of the invention a system for controlling attitude about pitch, yaw, and roll axes and axial thrust of a body is provided. The system comprises a main thrust generator located on an aft portion of the body. The aft portion of the body being aft of a calculated dynamic center of gravity of the body. A thrust vector controller (TVC) is connectable to the main thrust generator. The system also comprises at least one fast reaction control system (RCS), located on a forward portion of the body. The forward portion of the body being forward of the calculated dynamic center of gravity of the body. An RCS controller is connectable to, and synchronized with the RCS and the TVC.
In accordance with another embodiment the invention is directed towards an attitude control system for controlling momentum vector force about a center of gravity of a rocket. The system comprises a main propulsion nozzle having a main propulsion axis wherein the main propulsion nozzle is disposed aft of the center of gravity. The main propulsion nozzle is steered by a main propulsion controller. The system also comprises a forward located reaction control system having a plurality of selectively and independently controlled radial force generating nozzles. The plurality of radial force generating nozzles are synchronized to work in conjunction with at least one controllable aerodynamic vane and the main propulsion controller.
In accordance with another embodiment of the invention a rocket controller is provided. The rocket controller is disposed within a rocket having forward and aft sections, a central axis, and a dynamic center of gravity. The rocket controller comprises a principal thrust generator located aft of the rocket dynamic center of gravity and a thrust vector controller. The thrust vector controller is adapted to control the thrust generator. The rocket controller also comprises a second thrust generator located forward of the rocket dynamic center of gravity, and a second thrust vector controller. The second thrust vector controller is adapted to control the second thrust generator.
In accordance with another embodiment the invention includes a method for synchronizing forward and aft thrust vector control for a body traveling in a fluid. The body is adapted to minimizing fluid resistance and having forward and aft sections; and has a primary thrust generator disposed in the aft section, and a secondary thrust generator disposed in the forward section. The method comprises the steps of initiating the primary thrust generator and calculating a dynamic center of gravity for the traveling body. Next, the principal thrust axis generated by the primary thrust generator is calculated and compared with the calculated center of gravity to determine an offset between the principal thrust axis and the dynamic center of gravity. If the offset exceeds a predetermined value then the offset is adjusted to the predetermined value or lower by synchronized operation of the primary and secondary thrust generators.
The invention is also directed towards a program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine to perform method steps for synchronizing forward and aft thrust vector control for a body traveling in a fluid. The body is adapted to minimizing fluid resistance and having forward and aft sections, a primary thrust generator disposed in the aft section, and a secondary thrust generator disposed in the forward section. The method comprises the step of initiating the primary thrust generator and calculating a dynamic center of gravity for the traveling body. The next step calculates a principal thrust axis generated by the primary thrust generator and determines an offset between the principal thrust axis and the dynamic center of gravity. If the offset exceeds a predetermined value the next step adjusts the offset to the predetermined value, or lower. The step of adjusting the offset further comprises the step of calculating a torque required to adjust the offset to the predetermined value and initiating the secondary thrust generator to apply the calculated torque. In addition, the primary thrust generator is steered to assist in adjusting the offset to the predetermined value.